Bar for a chain saw

ABSTRACT

The present invention discloses a bar for a chain saw comprising a pair of parallel guide rails for a saw chain, a circumferential groove provided between said pair of guide rails and extending therealong, and an oil supply means having one or more ports facing to said groove, wherein a cover plate extending from one of said opening to a top portion of the bar is fixedly mounted within said groove and along a bottom portion thereof, thereby forming an oil passage, and oil supplied into the oil passage through said opening by the oil supply means can be discharged into the guide groove at the top portion of the bar.

0 United States Patent [1113,578,779

[72] inventor Kan lshizaki [56] References Cited Tokyo, J i UNITED STATES PATENTS gr 1233 3,l85,l9l 5/1965 Olsen 143/32 [45] Patented May 18,1971 3,313,186 4/1967 Rochon 77/68X [73] Assignee Shingu Shoko, Ltd. Primary Examiner-Donald R. Schran Otaru, Hokkaido, Japan Attorney-McGlew & Toren ABSTRACT: The present invention discloses a bar for a chain saw comprising a pair of parallel guide rails for a saw chain, a circumferential groove provided between said pair of guide 54] BAR FOR A CHAIN SAW rails and extendingftherealong, 51nd an oil sgpply rneans haiiing 1 Claim 28 Drawing Figs one or rnore ports acmg to sal groove, w erema cover p ate extending from one of said opening to a top portion of the bar [52] U.S. Cl 143/32 is fixedly mounted within said groove and along a bottom por- [51] Int. Cl ..B27b17/0 2, tion thereof, thereby forming an oil passage, and oil supplied B27b 17/12 into the oil passage through said opening by the oil supply [50] Field of Search 143/32, 32- means can be discharged into the guide groove at the top portion of the bar 7 sum 2 or 3 FIG. 4B FI6.4C 'F/ PATENTED m 1 8 :97:

FIG.6E

G. VII/m M0 A1 7 FIG. 60

FIG. 6A FIG. 68 FIG. 6C

mwswron. A nun/ml BY hwy/14W Armada/s v BAR FOR A CHAINSAW The present invention relates to a bar for a chain saw, more particularly an oil supply means in a bar for a chain saw.

The bar for a chain saw has generally an oil supply system provided with a discharge opening, near the base portion of the bar, from which oil is discharged into a guide groove for a saw chain. The saw chain normally travels along the rail or rails provided circumferentially of the bar at the velocity of more than 10 m./sec. And, oil supplied in the guide groove at the base portion of the bar scatters forwardly at the top portion thereof, due to centrifugal force during rotation of the saw chain. Consequently, when the saw chain passes through the top portion to locate at a cutting position, where coefficient of friction between the bar and the saw chain reaches to the maximum, supplied oil has been mostly lost. This is the serious problem in the conventional bar for a chain saw of the type.

A bar for a chain saw according to the present invention is a quite new and improved one which can not only cover the above-described problem of the conventional bar of the type,

but also attain the desired effect.

Accordingly, an object of the present invention is to provide a bar f a chain saw comprising a pair of parallel guide rails for a sa chain, a circumferential groove provided between said pair of guide rails and extending therealong, and an oil supply means having one or more ports facing to said groove, wherein a cover plate extending from one of said opening to a I top portion of the bar is fixedly mounted within said groove and along a bottom portion thereof, thereby forming an oil passage, and oil supplied into the oil passage through said .opening by the oil supply means can be discharged into the guide groove at the top portion of the bar.

In the accompanying drawings;

FIG. I is a partly longitudinal sectional side view of a bar for a chain saw, showing an embodiment having oil passages formed by a pair of upper and under cover plates, each extending from an opening of an oil supply means to a top portion of the bar;

FIG. 2 is a partly longitudinal sectional side view of another embodiment of the bar for a chain saw according to the present invention, shown likewise in FIG. 1, with the exception that an oil passage is formed by a single cover plate extending from one opening to other opening through a top portion of the bar;

FIG. 3 is a partly longitudinal sectional side view of a bar for a chain saw showing a further embodiment, likely to FIGS. 1 and 2, with the exception that a tubular cover plate is employed to form an oil passage;

FIG. 4 (A) through (D) are cross-sectional views, taken along the line IV-IV of FIG. I, particularly showing various modification of a cover plate forming an oil passage within the guide groove of the bar;

FIG. 5 (A) through (C) are cross-sectional views taken along the line V-V of FIG. 3, likely to FIG. 4, particularly showing various examples of a tubular cover plate;

FIG. 6 (A) through (E) are cross-sectional views taken along the line VI-VI of FIG. 1;

FIG. 7 (A) and (B) are cross-sectional views taken along the line VII-VII of FIG. 3;

FIG. 8 (A) through (I) show various examples of an opening I of the oil passage at the top portion of the bar; and

FIG. 9 (A) and (B) are partly longitudinal sectional views of a bar for'a chainsaw of the present invention, shown in part, particularly a means for sealing an end portion of an oil passage, near an opening of an oil supply means.

In the accompanying drawings, a main body 1 of a bar has a pair of parallel guide rails 3, along which a saw chain 2 travels in an arrow direction, and a guide groove 4 formed between said pair of parallel guide rails. The main body 1 of the bar is provided with an oil supply means having a discharge opening 5, at a base portion thereof, that is, one end portion of the bar nearer to an operator of the chain saw. Said oil supply means communicates with the guide groove 4 through an opening 6.

A cover plate 7 is fixedly mounted within said guide roove and extends from the opening 6 to the top portion of t e bar,

in a manner of forming, along a bottom portion of the guide groove, an oil passage 8 having one end communicating with said opening 6 at the base portion and other opening 9 at the top portion of the bar. The cover plate 7 may be of any of cross-sectional configurations as shown in FIG. 4, (A) through (D), FIG. 5, (A) through (C), FIG. 6, (A) through (F), and FIG. 7, (A) and (B). Various examples or modifications of the opening 9 are shown in FIG. 8, (A) through (I), The cover plate is selectively made of various kinds of oil-resistant materials such as metal or synthetic resin, and fixed within the guide groove by any suitable means, for example, welding, thermit welding, or bonding. In the bar for a chain saw of the type, uneven frictional loss inevitably occurs on surfaces of guide rails; in other words, coefficient of friction between the saw chain and the rail reaches to the maximum at surfaces of the downwardly positioned rails in FIG. 1, resulting in the local wear in this area. Such local wear or frictional loss on the rail surface can be eliminated in the present invention. That is, in the present invention, another oil passage within the under groove, as shown with the dotted line in FIG. I, is preferably provided symmetrically to that of the upper groove, so that the upper and under rails can be alternatively served. Instead of separate cover plates for forming upper and under oil passages, a single cover plate may be employed. If the single cover plate as shown in FIG. 3 is used, the cover plate is extended from the opening 6 communicating with the upper groove to an under opening 6' of the under groove by way of the top portion of the bar, and preferably provided with one or plural openings for discharging oil into the guide groove at places corresponding to the top portion of the bar or other desired places thereof (refer to FIG. 8, (A) through (1)). The cover plate 7 may be of a tubular shape, as shown in FIG. 3. The oil passage is sealed 7 at the base portion opposite to the top portion of the bar, as shown in FIG. 9, (A) and (B).

Iclaim:

l. A chain saw bar comprising a bar body having a top portion and at least one side with a pair of spaced parallel guide rails extending around the periphery thereof for a saw chain of the chain saw, a circumferential guide groove formed between said guide rails, oil supply means having at least one port o enin tosaid uide oove, atubular cover late mounted P g g 8 P 7 within said guide groove and extending along a bottom portion 

1. A chain saw bar comprising a bar body having a top portion and at least one side with a pair of spaced parallel guide rails extending around the periphery thereof for a saw chain of the chain saw, a circumferential guide groove formed between said guide rails, oil supply means having at least one port opening to said guide groove, a tubular cover plate mounted within said guide groove and extending along a bottom portion thereof and having a top surface forming the bottom of said groove which is engageable with the chain of the saw, said cover extending from said port to a top portion of said bar, said tubular cover defining an oil passage therein Having an oil discharging port provided at least at said top portion whereby oil supplied in the oil passage through said port is discharged into said guide groove and out said discharging port. 